The strange sensation of déjà vu: notso strange in temporal lobe epilepsyChris J A Moulin

He who is faithfully analysing many dif-ferent cases of epilepsy is doing far morethan studying epilepsy.Hughlings Jackson

Déjà vu is an infrequent and nebulousmental experience—a mismatch betweensubjective perceptions of memory andretrieval itself.1 Relative to other memoryerrors and illusions, it has not receivedmuch attention in scientific works.However, one area where déjá vu has beenstudied consistently is temporal lobe epi-lepsy (TLE)2 and in the spirit of HughlingsJackson, Warren-Gash and Zeman3 makean important contribution to this field.

There has been a constant problem withthe TLE literature and our understandingof déjà vu more generally. Despite the factthat in other domains we have learned agreat deal about cognition through thestudy of epilepsy—I would say cognitiveneuropsychology is indebted to it—therehas always been the idea that déjà vu inTLE is abnormal. The relationship betweenhealthy forms of the experience and itsnature in TLE has not been clear and it isthis important issue which Warren-Gashand Zeman address.

Using a detailed inventory, Warren-Gashand Zeman3 find prima facie evidence thatthere is a continuum between healthy déjàvu and the déjà vu experiences in TLE —

and that the two forms are phenomeno-logically the same. Warren-Gash andZeman3 show that where TLE patients andcontrols do differ is in the phenomenawhich occur alongside the déjà vu. This isbecause the minor glitch responsible fordéjà vu in healthy experiences may well dis-charge further and with more intensity inthe epileptic brain than it does in thehealthy brain.The findings are of clinical relevance.

There is nothing diagnostic in déjà vuper se, but one needs to look at triggersand associated phenomena (see4 formore on the clinical interpretation ofdéjà vu). Future research should considerwhether there is anything distinctiveabout déjà vu in other populationsthought to experience it more fre-quently: anxiety and dissociative disor-ders, for instance.Recent laboratory research on healthy

people has suggested that déjà vu iscaused by feelings of familiarity generatedby situations which appear to be familiarbut are known not to be.5 But it is unclearwhether these sorts of experience in suchdry tests of memory reach the evocativeheights of the ‘real’ déjà vu experience.1

In contrast, Warren-Gash and Zeman3

point to people with and without epilepsyhaving déjà vu of similar intensity andphenomenology. It now might be reason-able to suggest that there is the sameunderlying cause of deja vu in peoplewith and without epilepsy: déjà vu is asomewhat unpredictable neural event, aquirk of biology.

Competing interests None.

Provenance and peer review Commissioned;internally peer reviewed.

To cite Moulin CJA. J Neurol Neurosurg Psychiatry2014;85:132.

Received 30 November 2012Accepted 4 February 2013Published Online First 1 March 2013

▸ http://dx.doi.org/10.1136/jnnp-2012-303520

J Neurol Neurosurg Psychiatry 2014;85:132.doi:10.1136/jnnp-2012-303876

REFERENCES1 O’Connor AR, Moulin CJA. Recognition without

identification, erroneous familiarity, and déjà vu. CurrPsychiatr Rep 2010;12:165–73.

2 Illman NA, Butler CR, Souchay C, et al. Dejaexperiences in Temporal Lobe Epilepsy. Epilepsy ResTreat 2012;2012:1–40.

3 Warren-Gash C, Zeman A. Is there anything distinctiveabout epileptic deja vu? J Neurol Neurosurg Psychiatry2014;85:143–7.

4 Warren-Gash C, Zeman A. Déjà vu. Pract Neurol2003;3:106–9.

5 Cleary AM, Ryals AJ, Nomi JS. Can deja vu result fromsimilarity to a prior experience? Support for thesimilarity hypothesis of deja vu. Psychon B Rev2009;16:1082–8.

Correspondence to Chris J A Moulin, LEAD CNRSUMR 5022, University of Bourgogne, 21065 Dijon,France; christopher.moulin@u-bourgogne.fr

132 Moulin CJA. J Neurol Neurosurg Psychiatry February 2014 Vol 85 No 2

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